Fullerene-decorated PdCo nano-resistor network hydrogen sensors: sub-second response and parts-per-billion detection at room temperature

Hydrogen detection with rapid response and ultra-low detection limits remains a critical challenge for safety and energy applications. Here, we report a fullerene-decorated PdCo nano-resistor network sensor that integrates nanostructuring, alloying, and surface engineering approaches. The C₆₀ layer enhances sensor performance by increasing the surface-to-volume ratio, enabling fast hydrogen diffusion, relieving mechanical stress during cycling, and guiding nanostructure morphology. Our composite device (20 nm C₆₀/ 3 nm Teflon AF/ 5 nm Pd₆₃Co₃₇/ 30 nm Teflon AF) achieves a response time of 0.40 ± 0.06 s across 1 – 100 mbar H₂ and detects 40 ppb H₂ with a signal-to-noise ratio of 10 at room temperature. A poly(methyl methacrylate) (PMMA) topcoat further improves cycling stability and selectivity under 90% RH and interfering gases. This design provides a scalable approach and opens the door for future adaptation of porous carbon-based frameworks and polymeric interlayers to realize robust, high-performance hydrogen sensors for real-world applications.